My dog keeps scratching his ears. What might be wrong?

The following article is taken from the "Purina® Animal Instincts" Podcast Series. Learn more at www.purina.com.

Don’t just assume your dog’s ears itch if he scratches them frequently. It may be a sign of a painful infection. Other symptoms include ear discharge, a strange odor, and head shaking. If you notice these signs, call your veterinarian.

Dogs frequently develop ear infections because of their long el-shaped ear canals that easily trap dirt and moisture. Breeds with long, floppy ears and pups who swim frequently are the most susceptible. Parasites or allergies can also trigger an infection.

The best way to prevent ear problems in your dog is to try to keep his ears squeaky clean and to check them often for any discharge or odor. Ask your veterinarian how to use cotton balls and an ear cleaner.

To determine if your dog has a food allergy or food intolerance, your veterinarian can conduct a diet elimination trial. The goal of the trial is to identify, and then eliminate, the food source that is triggering your dog's allergic reaction. If your pet responds favorably to the diet trial and the symptoms disappear, food allergy or intolerance is the likely cause.

Bear in mind that food allergies cannot be diagnosed on the spot. A diet elimination trial typically lasts eight to 12 weeks, with the exact time frame determined by your veterinarian. You will need to carefully follow the diet plan recommended for your dog. During the trial, this special diet must be fed exclusively. The best dog food food for allergies can vary depending on each case.

In dogs, a food allergy or intolerance generally appears as gastrointestinal (GI) upset, leading to vomiting, diarrhea, excess gas or weight loss; or intense itching and scratching, which can involve the ears, face, feet, tail and stomach. Itching can result in red, irritated-looking skin.

Food allergy or intolerance can make both you and your dog miserable. So, it's important to see your veterinarian as soon as possible if your pet experiences any of these symptoms. He or she can work with you to choose a special dog food for your dog's allergies.

Allergy or intolerance to certain foods, such as seafood, milk or peanuts, is common among people. Dogs also can have food allergy or food tolerance issues, although their manifestation can be different from what people experience.

Does your itchy dog have a dog skin disease, or allergies?

It has been estimated that up to 15 percent of dogs suffer from skin allergies, or allergic dermatitis. Allergic reactions often lead to skin inflammation, and the most common sign of allergies is scratching. Signs generally occur seasonally, but can extend throughout the year. Allergies are not technically dog skin diseases, and they are treatable.

Food allergies can also cause gastrointestinal upset in dogs. You can find more information on gastrointestinal issues caused by allergy, and how to address them below.

An allergy is an adverse reaction involving the immune system. Causes of allergic dermatitis include:

inhaled allergens—molds, pollens and house dust

flea allergies—the dog is allergic to the saliva in the fleabite

contact dermatitis—caused by skin exposure to an irritating substance, such as soaps, flea collars, feathers or wool

food allergies—dogs allergic to their food usually show signs of allergic dermatitis year-round

Your veterinarian will consider all of these factors when determining the cause of a dog skin disease or allergic dermatitis in your puppy or dog.

Allergies typically appear between 1 and 3 years of age, but they may occur at any time. Some breeds are predisposed to developing allergies: West Highland White Terriers, Wirehaired Fox Terriers, Golden Retrievers, Labrador Retrievers, Lhasa Apsos, Bulldogs, English Setters, Irish Setters, Boxers, Dalmatians and Shar-Peis.

What causes skin allergies?

When a dog has been repeatedly exposed to an allergen, the immune system may produce antibodies that attach to specific cells in the body. These cells release inflammatory substances, which cause itchiness.

How to recognize the symptoms

Because itchiness is the hallmark sign of allergies, you may notice that your dog will often scratch his belly, flanks, and ears; or rub his face and chew at his paws. Itching and scratching can lead to secondary problems, such as generalized redness, hair loss, skin infections and darkened skin tone.

Diagnosing allergies

Provide your veterinarian with a complete history of your pet’s symptoms, including time of year allergic signs may appear, and what environmental factors your dog is exposed to during those times. Before determining the cause of your dog’s problem, your veterinarian will want to rule out external parasites, drug reactions, disease and food allergy. In severe cases, your veterinarian may recommend intradermal skin testing or blood tests to help pinpoint the exact cause of the allergic reaction.

Managing skin allergies

Your veterinarian may recommend a variety of treatments to help relieve your dog’s symptoms:

mild pet shampoos to help soothe the skin and remove allergens from the coat

medication

supplements

a therapeutic diet

Finding the best dog food for your dog's allergies can be difficult, but recent research shows that diets high in omega-3 fatty acids can help reduce itching and inflammation associated with allergic dermatitis. These fatty acids can reduce the production of pro-inflammatory agents that can lead to irritation and itching. It has been shown that if secondary infections are controlled, up to 50 percent of dogs with allergic dermatitis will improve with modifications in fatty acid intake. Your veterinarian can work with you to recommend a special dog food for sensitive skin.

Gastrointestinal upset: a common problem in the dog digestive system

Gastrointestinal disease is one of the most common reasons dogs are brought to their veterinarian. Some digestive problems can be a result of dog food allergies. You can find more information on gastrointestinal issues caused by food allergy, and how to address them above.

Some dog digestive problems may resolve once the dog digestive system is given a chance to rest. But more serious conditions could result in weight loss, dehydration and debilitation. Your veterinarian can determine the appropriate treatment.

Proper diagnosis of dog digestive problems is often a difficult challenge

With so many potential causes, diagnosing your dog’s problem can be a challenge for your veterinarian. To complicate matters even more, the disorder can originate in any part of the dog digestive system, from the mouth and esophagus, to the stomach, liver, pancreas and intestinal tract.

Effective treatment for your dog

If additional diagnostic tests are needed, your veterinarian may recommend laboratory analyses, radiographs, or a procedure like endoscopy, which involves inserting a tube with a small video camera into your dog’s digestive tract. This can help visualize the problem.

Since many gastrointestinal disorders can irritate the stomach and intestine, a diet that’s easily digested can help ensure your dog gets the nutrient balance necessary to support recovery.

Two approaches to dietary management help resolve digestive system problems

Diet can play an important role in helping your dog recover from gastrointestinal distress. Some gastrointestinal tract conditions respond to a low fat, highly digestible diet. Other gastrointestinal conditions are fiber-responsive and require a diet with moderate fiber content. Your veterinarian will know which is best for your dog.

Allergies in dogs: food allergies are an irritating health problem for dogs

It's estimated that food allergies account for 10 to 15 percent of all dog allergies. A food allergy is an adverse reaction by the immune system to ingredients in the diet. This typically results in intense itching or intestinal upset.

While allergies in dogs can happen at any age, many cases are first seen in dogs under six months of age, or in those six years of age and older. Some breeds may be genetically predisposed to food allergies: Golden Retrievers, Labrador Retrievers, Cocker Spaniels, Shar-Peis, Dalmatians, Poodles, German Shepherds, Boxers and Bulldogs.

How to recognize symptoms of dog allergies

Unlike flea or environmental allergies, which are usually seasonal, food allergies tend to occur all year long. Generally, the symptoms of allergies in dogs involve either the skin or digestive systems.

Gastrointestinal symptoms in dog allergies may include:

Understanding allergic reactions to food

A food allergy is an immune-mediated reaction. The dog produces antibodies against components of food that are normally considered harmless. This differs from a food intolerance, such as lactose intolerance, which is an adverse reaction to a food, without involvement of the immune system.

Some dogs may become allergic to a diet after just a few days, while others may eat a particular food for many years before becoming allergic.

Allergens, the components of food that stimulate an allergy, are almost exclusively protein, such as the protein found in beef, wheat, chicken and dairy. Any protein normally used in foods can cause an allergy, but the size and structure of the protein, as well as the amount of exposure the dog has to the protein can influence whether or not an allergic reaction is initiated.

Natural defenses to food allergy

Fortunately, dogs have several natural defense mechanisms that can help prevent protein from stimulating an allergic response:

The digestive tract breaks protein into smaller fragments that are less likely to initiate an allergic reaction.

The lining of the digestive tract acts as a physical barrier to prevent the uptake of large protein molecules.

The normal immune system has a unique ability to respond to harmful substances, while remaining tolerant to dietary components.

Diagnosing allergies in dogs

There is no simple, rapid test to diagnose a food allergy, but an elimination diet feeding trial, under the direction of your veterinarian, is an effective and reliable method that can help confirm a diagnosis. It requires dedication and a significant time commitment, but if your pet shows improvement, it's well worth the effort and can help you find the best dog food for your dog's allergies.

For an elimination diet trial:

Feed a diet that contains a single protein and a single carbohydrate that your dog has not been exposed to before.

This diet must be fed exclusively for a period of 8 to 10 weeks, and possibly up to 12 weeks.

A hypoallergenic diet can also be used in an elimination diet trial.

If your dog's symptoms resolve during the elimination diet feeding trial, a diagnosis of food allergy is likely. The diagnosis is confirmed when your dog is fed his original diet, and the allergic symptoms reappear.

Modified protein strategy

Once the offending protein is identified, your veterinarian may recommend a hypoallergenic diet consisting of modified protein, which is less likely to elicit an allergic reaction. Essentially, the protein molecules are broken down to smaller particles and the resulting protein is considered hypoallergenic. Follow your veterinarian's directions carefully, and feed your dog only the recommended diet.

What are some ways that Veterinarians Diagnose Food Allergies in Dogs?

Environmental contaminants, such as dust and mold, can cause allergies in your dog. So can his food, although it takes time to make that diagnosis. Kim Horne, a Veterinary Technician at the University of Minnesota Veterinary Medical Center, explains: “we usually will put them on a food elimination diet trial.”

That means the dog spends eight to ten weeks on a new diet, eating protein and carbohydrate sources it hasn’t had before. Then it goes back to its original diet, and its responses are monitored. Horne says if the animal is truly allergic to food, there will likely be an increase in clinical signs, such as itching and inflamed skin. If these appear, various foods will be tried until one is found that doesn’t trigger the allergy symptoms. The best dog food for a dog's allergies can vary depending on the specifics of each case.